In the 1966 case of Reitman v. Mulkey, the U.S Supreme Court ruled against a California constitutional amendment that allowed property owners to refuse to sell or rent their properties on any grounds they chose, including racial discrimination. The court held that this amendment was unconstitutional because it violated the Equal Protection Clause of the Fourteenth Amendment by encouraging and involving state action in racial discrimination in housing markets. This decision marked an important step forward for civil rights as it effectively outlawed private racial covenants on real estate sales and rentals, which had been used as a tool for maintaining residential segregation.

In the dissenting opinion for REITMAN et al. v. MULKEY et al., Justice Harlan argued that the majority's decision was a significant departure from established constitutional principles, particularly those related to state action and equal protection. He contended that California's Proposition 14 did not involve any discriminatory state action but merely allowed private individuals to make their own decisions regarding property sales or rentals without government interference. The proposition, he asserted, did not promote racial discrimination; it simply removed anti-discrimination laws from housing transactions in the private sector. Therefore, according to him, this case should have been viewed as an issue of states' rights rather than one of racial discrimination under the Fourteenth Amendment’s Equal Protection Clause.